1. Field of the Invention
The present invention relates generally to thermal gradient producing systems, and more particularly to a ground source heat pump device and system capable of utilizing a shallow body of groundwater as a source for thermal exchange.
2. Description of Related Art
As fossil fuels and other natural resources become more scarce, communities across the globe are looking for new ways to reduce power consumption by increasing the efficiency of every day items such as air conditioning and heat pump systems.
Conventional air source heat pumps act as a thermal gradient producing device by depositing and/or removing heat from a designated or “conditioned space.” For example, in the cooling mode, the heat pump absorbs heat from the conditioned space and dissipates the heat into the warmer outside air environment. In the heating mode, the air source heat pump absorbs heat from the outside air environment and dissipates the heat into the conditioned air environment. However, as the temperature difference between the conditioned space and the outside environment increases, heat pumps must work harder to collect and dissipate the heat, thus depending on the season, or even the time of day, the heat pump's efficiency and effectiveness can vary greatly.
Moreover, it is known that liquids are a substantially better thermal transport medium than air. For this reason, liquid transfer mediums have been introduced into heat pumps in order to achieve a higher efficiency. There have been previous devices directed towards heat pump systems that utilize a fluid as the exchange medium between the heat pump system and the earth. Of these, there are essentially two types, the closed loop system and the open loop system.
Closed loop liquid thermal exchange systems typically utilize an underground tank or channels containing a thermal exchange liquid that is pumped through the heat exchanger of the heat pump in a sealed manner. By installing the tank underground, the system can take advantage of the relatively stable underground temperature, thereby preventing large fluctuations in the temperature of the exchange liquid when compared to the outside air. Accordingly, an overall improvement in the coefficient of performance of the heat pump unit itself can be achieved. However, closed loop thermal exchange systems require a significant amount of linear earth contact to ensure an effective exchange of thermal energy between the ground source heat pump system and the subterranean ground. To this end, it is often necessary to provide one or more bores or trenches that may be extremely deep or long, which are labor intensive and extremely costly to install.
Open loop liquid thermal exchange systems operate in a similar fashion to the closed loop systems but do not require a sealed tank or channels that must be buried underground. The open loop system instead utilizes shallow groundwater as the thermal exchange liquid. As such, it is necessary to include a well pumping device capable of pumping the groundwater from a shallow underground source, through the well pipe and into the heat pump system. However, most meaningful energy savings achieved by the heat pump unit is lost due to the operation of the well pump. Moreover, there is also the problem of where to dispose of the groundwater once it has been utilized by the system. In many instances, the groundwater output is inputted into an irrigation system, thus making the system even less efficient.
Accordingly, there remains a need for a hybrid-type ground source heat pump system that combines the energy efficiency of the closed loop system with the cost effectiveness and ease of installation allowed by the open loop system, and without the disadvantages of each.